Field of the Disclosure
The present disclosure relates to blood separation systems and methods. More particularly, the present disclosure relates to single-stage blood separation chambers and methods for separating blood in such chambers.
Description of Related Art
Various blood processing systems now make it possible to collect particular blood constituents, rather than whole blood, from donors. Typically, in such systems, whole blood is drawn from a donor, the particular blood component or constituent is removed and collected, and the remaining blood constituents are returned to the donor. By thus removing only particular constituents, potentially less time is needed for the donor's body to return to normal, and donations can be made at more frequent intervals than when whole blood is collected. This increases the overall supply of blood constituents, such as plasma and platelets, made available for health care.
Such systems may also be used for non-donation processing of a patient's blood. For example, whole blood may be drawn from a patient, with one component being removed and discarded (rather than being collected for donation). The remaining blood components may then be returned to the patient, along with a replacement fluid, if necessary. In other procedures in which the blood of a patient is being processed, at least one of the separated components may be collected, rather than all of the components being either returned to the patient or discarded.
Whole blood is typically separated into its constituents through centrifugation. This requires that the whole blood be passed through a centrifuge after it is withdrawn from, and before it is returned to, the donor or patient. To avoid contamination and possible infection of the donor, the blood is typically contained within a sealed, sterile fluid flow system during the entire centrifugation process. Typical blood processing systems thus include a permanent, reusable centrifuge assembly containing the hardware (drive system, pumps, valve actuators, programmable controller, and the like) that spins and pumps the blood, and a disposable, sealed and sterile fluid processing assembly that is mounted in cooperation on the hardware. The centrifuge assembly engages and spins a disposable centrifuge chamber of the fluid processing assembly during a collection procedure. The blood, however, makes actual contact only with the fluid processing assembly, which assembly is used only once and then discarded. Exemplary centrifuges and disposable processing assemblies are shown and described in U.S. Pat. Nos. 6,254,784 and 6,312,607, both of which are incorporated herein by reference.
As the whole blood is spun by the centrifuge, the heavier (greater specific gravity) components, such as red blood cells, move radially outwardly away from the center of rotation toward the outer or “high-G” wall of a separation chamber included as part of the fluid processing assembly. The lighter (lower specific gravity) components, such as plasma, migrate toward the inner or “low-G” wall of the separation chamber. Various ones of these components can be selectively removed from the whole blood by forming appropriately located channeling seals and outlet ports in the separation chamber of the fluid processing assembly. For example, therapeutic plasma exchange involves separating plasma from cellular blood components, collecting and disposing of the plasma, and returning the cellular blood components and a replacement fluid to the patient.
One possible disadvantage of known blood separation chambers is that they are typically suitable for only one type of blood separation procedure, thereby requiring the use of a different disposable processing assembly depending on the components into which the blood is to be separated. Accordingly, the need remains for a blood separation chamber that is capable of being used in a variety of different blood separation procedures.